JP2007270017A - Emulsion, process for its production and water-based paint composition using the emulsion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an emulsion containing a hydrophobic paint additive at high concentration in its outer envelope. <P>SOLUTION: The emulsion is a resin fine particle dispersion in an aqueous medium. The resin particles consists of an outer envelope formed with a resin enclosing a paint additive with average particle size of 100-500 nm. The solubility of the paint additive in water is less than 1 g/100 g. Preferably, the paint additive is at least one selected from a group consisting of a curing catalyst, a defoaming agent, a surface modifier, a leveling agent, an UV absorbing agent and an antioxidant. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an emulsion, a method for producing the same, and an aqueous coating composition using the emulsion. More specifically, the present invention relates to an emulsion containing a high concentration of a hydrophobic paint additive in the outer shell, and an aqueous paint composition using the emulsion, and further relates to a simple method for producing such an emulsion. .

  In recent years, from the viewpoint of environmental protection, there is a social demand for switching from solvent-based paints to water-based paints.

  In general, various paint additives are blended in the water-based paint composition in order to maintain its function or enhance commercial properties. Examples of the paint additive include an antioxidant, a surface conditioner, an ultraviolet absorber, and a light stabilizer. Among these additives, there are those which are highly hydrophobic and cannot be blended in the water-based paint because they are separated or aggregated as they are.

Patent document 1 is disclosing the copolymer emulsion containing a ultraviolet absorber and a light stabilizer. However, the copolymer emulsion described in Patent Document 1 only contains the above-mentioned additive accompanying the binder component as a main component. Therefore, it is practically impossible to use the emulsion itself as an additive for practical use.
JP 2002-285045 A

  The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to provide an emulsion and an aqueous coating composition containing a high concentration of an additive for hydrophobic coating in the outer shell, and its It is in providing the simple manufacturing method of such an emulsion.

  The emulsion of the present invention is an emulsion in which resin particles are dispersed in an aqueous medium. The resin particles include an outer shell made of resin and a coating additive contained in the outer shell. The solubility of the paint additive in water is less than 1 g / 100 g. The average particle size of the emulsion is 100 nm to 500 nm.

  In preferable embodiment, the solid content mass of the said additive for coating materials is 5-80 mass% with respect to the total solid content mass of an emulsion.

  In a preferred embodiment, the paint additive is at least one selected from the group consisting of a curing catalyst, an antifoaming agent, a surface conditioner, a leveling agent, an ultraviolet absorber and an antioxidant.

  In a preferred embodiment, the resin constituting the outer shell has a number average molecular weight of 3,000 to 50,000. In a preferred embodiment, the solubility parameter of the resin constituting the outer shell is 13 or less.

  An emulsion according to another embodiment of the present invention is an emulsion obtained by a miniemulsion polymerization method, in which resin particles are dispersed in an aqueous medium. The resin particles include an outer shell made of resin and a coating additive contained in the outer shell, and an average particle diameter thereof is 100 nm to 500 nm. The solubility of the paint additive in water is less than 1 g / 100 g. The outer shell is formed by polymerizing a pre-emulsion in which monomer mixture particles containing a coating additive are dispersed in an aqueous medium.

  According to another aspect of the present invention, a method for producing an emulsion is provided. In this production method, a coating additive having a solubility in water of less than 1 g / 100 g and a monomer mixture are dispersed in an aqueous medium, and the monomer mixture particles containing the coating additive are dispersed in the aqueous medium. Preparing a pre-emulsion; and polymerizing the monomer mixture in the pre-emulsion to obtain an emulsion in which resin particles encapsulating the coating additive are dispersed in an aqueous medium. The average particle diameter of the resin particles is 100 nm to 500 nm.

  According to still another aspect of the present invention, an aqueous coating composition is provided. This aqueous coating composition contains the above emulsion and a binder component.

  According to the present invention, the hydrophobic paint additive can be applied to the aqueous paint by encapsulating the hydrophobic paint additive in the outer shell of the resin particles of the emulsion. In addition, by taking such a so-called encapsulated form, the additive can be more stably present than when the additive for paint is simply dispersed, so that the function of the additive is more effective. Can be demonstrated.

A. Overall Configuration of Emulsion The emulsion of the present invention is an emulsion in which resin particles are dispersed in an aqueous medium. The resin particles include an outer shell made of resin and a coating additive contained in the outer shell. It is not necessary for the outer shell to completely cover the coating additive to be included, and it is sufficient that the outer shell can be stably present in the aqueous medium as resin particles. The average particle diameter of the resin particles is 100 nm to 500 nm, preferably 100 nm to 300 nm. If the average particle diameter of the resin particles in the emulsion is in such a range, an emulsion excellent in dispersion stability that does not produce aggregates and precipitates can be obtained. The solid content of the emulsion (that is, the total solid content of the outer shell resin and the coating additive) is preferably 20 to 50% by mass. The average particle size of the resin particles is a value obtained by diluting the sample with deionized water and measuring the sample at 25 ° C. using a laser scattering particle size distribution analyzer (trade name ELS-800, manufactured by Otsuka Electronics Co., Ltd.). is there.

B. Paint Additive The paint additive has a solubility in 100 g of water of less than 1 g / 100 g, preferably less than 0.5 g / 100 g, more preferably less than 0.1 g / 100 g. The solubility in water can be measured by the following method: 50 g of ion-exchanged water and 0.5 g of a sample (here, paint additive) are placed in a 100 mL plastic sample tube, and a touch mixer (Yamato Science) is used. Stir for 1 minute using MT-51, manufactured by Co., Ltd. (driving condition: number of rotary dials 10). After stirring, the contents of the plastic sample tube are visually observed to evaluate whether the sample is completely dissolved. When the sample is not completely dissolved, it is determined that the water solubility is less than 1 g / 100 g. When the sample is completely dissolved, it is determined that the water solubility is 1 g / 100 g or more. Similarly, by setting the amount of the sample put into the plastic sample tube to 0.25 g and 0.05 g, it is determined whether the water solubility is less than 0.5 g / 100 g and less than 0.1 g / 100 g, respectively. .

  Specific examples of the coating additive include a curing catalyst, a pH adjuster (for example, triethylamine), an antifoaming agent, a leveling agent, an ultraviolet absorber, an antioxidant, a flame retardant, an antistatic agent, a compatibilizing agent, and a crosslinking agent. Agents, thickeners, electrostatic assistants, plasticizers, heat stabilizers, light stabilizers, surface conditioners and the like. Preferred paint additives include curing catalysts, antifoaming agents, surface conditioners, leveling agents, ultraviolet absorbers, antioxidants and combinations thereof. The paint additives can be used alone or in combination of two or more.

  Specific examples of the curing catalyst include organic amine compounds having 6 or more carbon atoms such as 1,4-diazabicyclo [2.2.2] octane and 1,8-diazabicyclo [5.4.0] undecene-7; Examples thereof include organometallic compounds such as dibutyltin dilaurate, dibutyltin diacetate, tin dioctylate, and cobalt naphthenate.

  Specific examples of the antifoaming agent include foam-breaking polysiloxane, alkyl methacrylate / styrene copolymer, butadiene copolymer / polyalkylsiloxane mixture, polyalkyl methacrylate, and the like.

  The surface conditioning agent and the leveling agent include a material having any appropriate surface conditioning function depending on the purpose. Specific examples of the material having the surface adjusting function include polyether-modified siloxane, polyester-modified polymethylalkylsiloxane, polyether-modified polydimethylsiloxane, and acrylic group-containing polyether-modified polydimethylsiloxane.

  Specific examples of the ultraviolet absorber include 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, ethanediamide-N- (2-ethoxyphenyl). -N '-(4-isododecylphenyl) and the like.

  Specific examples of the antioxidant include hindered phenol antioxidants, hindered amine antioxidants, and the like.

  The solid content mass of the paint additive is preferably 5 to 80 mass%, more preferably 5 to 50 mass%, based on the total solid mass of the emulsion. By containing the paint additive at such a high concentration, the function of the additive can be satisfactorily exhibited in the aqueous paint. It is one of the achievements of the present invention that an emulsion in which only the additive is contained in the outer shell at such a high concentration is actually prepared.

C. Outer shell containing paint additive The outer shell contains the paint additive. The outer shell is made of any appropriate resin. By encapsulating the paint additive in the resin shell, even a hydrophobic paint additive can be applied to the aqueous paint.

ここで、Ｖ_ｍｌはヘキサンによる滴定終了時の混合溶媒の分子容であり、Ｖ_ｍｈは水による滴定終了時の混合溶媒の分子容である。δ_ｍｌおよびδ_ｍｈは、それぞれヘキサンまたは水による滴定終了時の混合溶媒の溶解性パラメーターであり、以下の式で表される。

ここで、δ_{ｗａｔｅｒ}およびδ_{ｈｅｘａｎｅ}は、それぞれ水およびヘキサンの溶解性パラメーターであり、δ_ｇは良溶媒の溶解性パラメーターである。φ_ｍｌは混合溶媒中のヘキサンの体積分率であり、φ_ｍｈは混合溶媒中の水の体積分率である。 The solubility parameter of the resin is preferably 13 or less, more preferably 12-8. If the solubility parameter is greater than 13, the polarity may be too strong to form an emulsion. In addition, since the solubility parameter of water is 23.5, the solubility parameter of resin can be 13.5 as a threshold value which can carry out emulsion polymerization by an aqueous system, for example. On the other hand, if the solubility parameter is too small, the paint additive may not dissolve in the monomer mixture. As used herein, “solubility parameter” refers to a parameter proposed by Hildebrand and is defined by the square root of the cohesive energy density. Typical solvent and resin solubility parameters are described, for example, in the Polymer Handbook. In the present specification, the solubility parameter of the resin is determined, for example, by the following procedure: 0.5 g of resin is weighed into a beaker, and 10 ml of a good solvent (for example, acetone, dioxane, butyl cellosolve, THF) is added. Add with a whole pipette to dissolve the resin and prepare a resin solution. This resin solution is kept at 20 ° C., water or hexane is added dropwise, and the point at which it becomes cloudy is used as a titration value. From this titration value, the solubility parameter δ _resin of the _resin is calculated using the following equation.

Here, V _ml is the molecular volume of the mixed solvent at the end of titration with hexane, and V _mh is the molecular volume of the mixed solvent at the end of titration with water. δ _ml and δ _mh are solubility parameters of the mixed solvent at the end of titration with hexane or water, respectively, and are represented by the following equations.

Here, δ _water and δ _hexane are water and hexane solubility parameters, respectively, and δ _g is a good solvent solubility parameter. φ _ml is the volume fraction of hexane in the mixed solvent, and φ _mh is the volume fraction of water in the mixed solvent.

  The resin constituting the outer shell is typically a homopolymer or copolymer having a repeating unit derived from an ethylenically unsaturated monomer. Specific examples of the ethylenically unsaturated monomer include methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, n-butyl acrylate, isobutyl methacrylate, isobutyl acrylate, and t-methacrylic acid. -Butyl, t-butyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, lauryl methacrylate, phenyl acrylate, isobornyl methacrylate, isobornyl acrylate, cyclohexyl methacrylate, t-butylcyclohexyl methacrylate, acrylic acid t-butylcyclohexyl, dicyclopentadienyl methacrylate, dicyclopentadienyl acrylate, dihydrodicyclopentadienyl methacrylate, dihydrodicyclopentadienyl acrylate Any (meth) acrylic acid ester; styrene monomer such as styrene, α-methylstyrene, t-butylstyrene, parachlorostyrene, vinylnaphthalene; methacrylamide, acrylamide, N-methylolmethacrylamide, N-methylolacrylamide, N- Butoxymethyl methacrylamide, N-butoxymethyl acrylamide, N, N-dimethyl methacrylamide, N, N-dimethyl acrylamide, N, N-dibutyl methacrylamide, N, N-dibutyl acrylamide, N, N-dioctyl methacrylamide, N , N-dioctylacrylamide, N-monobutylmethacrylamide, N-monobutylacrylamide, N-monooctylmethacrylamide, N-monooctylacrylamide, N- (2-hydroxyethyl) ) Amide monomers such as acrylamide and N- (2-hydroxyethyl) methacrylamide; vinyl ketones; half esters of (meth) acrylic acid and C2-C8 diols [for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (Meth) acrylates, 3-hydroxypropyl (meth) acrylates, hydroxybutyl (meth) acrylates] and their ε-capracactone modified products. These monomers can be used alone or in combination of two or more. The number, type, combination and amount of ethylenically unsaturated monomers used can be further increased so long as they can be emulsified and yield monomer mixture particles and resin particles having the desired average particle size. As long as the outer shell resin having the above can be obtained, it can be appropriately set according to the purpose. Moreover, you may copolymerize the said ethylenically unsaturated monomer and arbitrary appropriate other monomers copolymerizable with the said ethylenically unsaturated monomer.

  The number average molecular weight of the resin constituting the outer shell is preferably 3,000 to 50,000. When the molecular weight is less than 3,000, the water resistance of the coating film obtained when applied to a water-based paint may be insufficient. If the molecular weight exceeds 50,000, the appearance of the coating film may be impaired.

D. Method for Producing Emulsion The emulsion of the present invention can be prepared by a miniemulsion polymerization method. In the miniemulsion polymerization method, the additive for paint and a monomer mixture containing an ethylenically unsaturated monomer are dispersed in an aqueous medium, and the monomer mixture particles containing the additive for paint are dispersed in the aqueous medium. Preparing a prepared pre-emulsion; and polymerizing a monomer mixture in the pre-emulsion to obtain an emulsion in which resin particles encapsulating the coating additive are dispersed in an aqueous medium. By using the mini-emulsion polymerization method, it is possible to encapsulate the resin additive in the resin particles without causing the monomer to diffuse and move from the pre-emulsion oil droplets into the water to undergo emulsion polymerization. As a result, the paint additive can be applied to the aqueous composition, and a coating film excellent in uniformity can be obtained. Hereinafter, a specific procedure in an example of the miniemulsion polymerization method used in the present invention will be described.

  First, a monomer mixture is prepared. The monomer mixture is prepared, for example, by mixing the ethylenically unsaturated monomer and, if necessary, the other copolymerizable monomer at a predetermined ratio according to the purpose. The monomer mixture may be pre-emulsified using any suitable disperser (eg, homomixer, dispermixer).

  Next, a pre-emulsion is obtained by emulsifying the obtained monomer mixture, the paint additive, the emulsifier, and any other appropriate additive as necessary using a high-speed shear emulsifier. According to the production method of the present invention, it is possible to realize a pre-emulsion in which the monomer mixture particles are dispersed in the aqueous dispersion medium in a state in which the paint additive is included. The average particle size of the monomer mixture particles in the pre-emulsion is preferably set to 0.5 to 1.5 times, more preferably 0.8 to 1.2 times the average particle size of the resin particles in the resulting emulsion. obtain. More specifically, the average particle size of the monomer mixture particles is preferably 100 nm to 400 nm, and more preferably 100 nm to 300 nm. When the monomer mixture particles have an average particle diameter in such a range, aggregation of the coating additive at the time of forming the emulsion and preparing the aqueous coating material can be prevented. As a result, when the resulting emulsion is applied to an aqueous paint, the paint additive can function very adequately. The average particle size of the monomer mixture particles can be controlled by adjusting the amount of emulsifier and shearing conditions (eg, rotational speed, shear stress, shear time, pressure at shear).

  Any appropriate apparatus can be adopted as the high-speed shearing emulsifier as long as a desired pre-emulsion can be obtained. Specific examples include a high-speed rotary shear type stirrer, a colloid mill, a high-pressure colloid mill, a high-pressure jet type emulsifier / disperser, an ultrasonic emulsifier / disperser, and a high-pressure homogenizer. For example, a high-speed rotary shear type stirrer atomizes a liquid by utilizing a strong shearing effect and / or impact force that occurs in a minute gap between a rotary blade and a stationary ring. T. as a stirrer. The rotation speed when using K-Robomix (registered trademark; manufactured by Primix Co., Ltd.) is, for example, 10,000 to 20,000 rpm, and the stirring time is, for example, 5 to 60 minutes. Therefore, it is preferable to control the stirrer so that the peripheral speed is 10 to 30 m / sec.

  As the emulsifier, an anionic emulsifier or a nonionic emulsifier is typically used. Specific examples of anionic emulsifiers include dodecyl benzene sulfonate, lauryl sulfate, alkyl diphenyl ether disulfonate, dialkyl sulfosuccinate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene polycyclic phenyl ether sulfate, poly Examples thereof include oxyethylene alkyl ether sulfates. Specific examples of the nonionic emulsifier include polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene polycyclic phenyl ether, polyoxyethylene sorbitan fatty acid ester and the like. The addition amount of the emulsifier is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the monomer mixture. When the amount of the emulsifier is less than 1 part by mass, there is a possibility that an aggregate is formed during the production of the emulsion. If the amount of the emulsifier exceeds 15 parts by mass, the water resistance of the resulting coating film may be reduced.

  The emulsifier may be a reactive emulsifier. A reactive emulsifier is a surfactant having an ethylenically unsaturated bond. Reactive emulsifiers are classified into three types: anionic, cationic and nonionic. The reactive emulsifier may be used in combination with the above normal emulsifier, or may be used alone. A reactive emulsifier may be included in the monomer mixture. When the reactive emulsifier is used, the amount used (the total of the reactive emulsifier and the normal emulsifier when used in combination with the above ordinary emulsifier) is 1 to 15 parts by mass with respect to 100 parts by mass of the monomer mixture. In addition, when a reactive emulsifier is included in the monomer mixture and the reactive emulsifier has an ionic group (that is, an anionic type or a cationic type), the amount used is preferably 5 It is below mass parts.

  Specific examples of commercially available anionic reactive emulsifiers include Eleminol JS series (manufactured by Sanyo Kasei Kogyo Co., Ltd.), Laterum S series, Latemu PD series, SASK series (manufactured by Kao Corporation), Aqualon HS series (manufactured by Daiichi Kogyo Seiyaku Co., Ltd. ), Adekaria soap SE, SR series (Asahi Denka Co., Ltd.), Antox MS-60 (Nippon Emulsifier Co., Ltd.) and the like. Specific examples of commercially available cationic reactive emulsifiers include Latemul K series (manufactured by Kao Corporation). Specific examples of commercially available nonionic reactive emulsifiers include Aqualon RN series (Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria soap NE, ER series (Asahi Denka Co., Ltd.) and the like.

  Specific examples of the additive include a polymerization initiator and a chain transfer agent.

  The polymerization initiator may be either oil-soluble or water-soluble. Examples of the oil-soluble polymerization initiator include organic peroxides such as benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, octanoyl peroxide, stearoyl peroxide; azobisiso Examples thereof include azo compounds such as butyronitrile, 2,2′-azobis (2-methylbutyronitrile), and 2,2′-azobis (2,4-dimethylvaleronitrile). Examples of water-soluble polymerization initiators include cumene hydroperoxide, t-butyl peroxide, t-butyl peroxylaurate, t-butyl peroxyisopropyl carbonate, t-butyl peroxyacetate, and diisopropylbenzene hydroperoxide. Organic peroxides: azobis (2-methylpropiononitrile), 4,4′-azobis (4-cyanobutanoic acid), dimethylazobis (2-methylpropionate), azobis [2-methyl-N- (2- Azo compounds such as hydroxyethyl) -propionamide] and azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}; persulfates such as potassium persulfate, ammonium persulfate and sodium persulfate Is mentioned. These may be used alone or in combination of two or more. If necessary, a reducing agent such as sugar, sodium formaldehyde sulfoxylate, or iron complex may be used in combination with the polymerization initiator to form a redox polymerization system. The polymerization initiator can be preferably used at a ratio of 0.1 to 3 parts by mass with respect to 100 parts by mass of the monomer mixture.

  Any appropriate chain transfer agent capable of adjusting the molecular weight of the resin constituting the outer shell to a desired range can be adopted as the chain transfer agent. Specific examples include lauryl mercaptan, t-dodecyl mercaptan, octyl mercaptan, 2-ethylhexyl thioglycolate, 2-methyl-5-t-butylthiophenol, α-methylstyrene dimer, and the like. The chain transfer agent can be preferably used at a ratio of 0.5 to 5 parts by mass with respect to 100 parts by mass of the monomer mixture.

  Next, the pre-emulsion is subjected to miniemulsion polymerization to obtain an emulsion. The pre-emulsion dispersed in the aqueous dispersion medium with the monomer mixture particles encapsulating the coating additive is polymerized by miniemulsion polymerization so that the monomer mixture is polymerized while encapsulating the coating additive. Form a shell. As a result, an emulsion in which resin particles encapsulating the paint additive (that is, capsule-like resin particles) are dispersed is obtained. The polymerization conditions can be appropriately selected according to the type of monomer used in the monomer mixture, the content of paint additives, and the like. In one embodiment, the polymerization temperature in the miniemulsion polymerization is 40 to 100 ° C., and the polymerization time is 4 to 8 hours. As described above, the emulsion of the present invention is obtained.

E. Aqueous paint composition The aqueous paint composition of the present invention contains the above emulsion and a binder component. As the binder component, any appropriate resin applicable to the binder of the water-based paint can be adopted. The solid content concentration of the binder component in the aqueous coating composition is preferably 30 to 90% by mass, more preferably 40 to 60% by mass. The coating composition of the present invention may further contain a coloring material (for example, pigment) and other resin components depending on the purpose.

  The solid content of the emulsion in the aqueous coating composition is preferably 1 to 90 mass%, more preferably 10 to 80 mass%, based on the total solid content of the aqueous coating composition. When the solid content ratio of the emulsion is less than 1% by mass, the function of the paint additive may not be sufficiently exhibited. When the solid content ratio of the emulsion is larger than 90% by mass, the content of the binder component is reduced as a result, so that the coating film may not be sufficiently formed.

  The water-based paint composition of the present invention is a clear paint, enamel paint, architectural use, automotive exterior coating, automotive parts and other coating applications, printing ink and other coating materials, nonwoven fabric bonding agents, adhesives, fillers, It can be suitably used for forming materials, resists, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on mass.

Example 1 Preparation of Additive Emulsion for Additive for Coating (Antifoaming Agent) Deionized water 600 was added to a 5 L stainless steel beaker equipped with a stirrer (trade name TK Robotics (registered trademark) manufactured by PRIMIX Corporation). Part, Latemul PD-104 (trade name, manufactured by Kao Corporation, 20% reactive surfactant aqueous solution) was added. While stirring this at 2000 rpm, 800 parts of monomers (40 parts of styrene, 154 parts of methyl methacrylate, 196 parts of methyl acrylate, 275 parts of ethyl acrylate, 123 parts of 4-hydroxybutyl acrylate, 12 parts of methacrylic acid), dodecyl mercaptan (Chain transfer agent) 8 parts and an antifoaming agent (BIC Chemie Japan KK make, brand name BYK-094, non-volatile content 98%) which were uniformly mixed were gradually added to obtain a primary emulsion. This was emulsified at 12000 rpm for 20 minutes while cooling with ice water to obtain a pre-emulsion. The particle diameter of the obtained pre-emulsion was measured by Otsuka Electronics Co., Ltd., brand name ELS-800. The average particle size of the monomer mixture particles in the pre-emulsion was 260 nm.

  Next, 831 parts of deionized water was charged into a 5 L vertical flask equipped with a stirrer, thermometer, cooling pipe, nitrogen gas introduction pipe and water bath, and the temperature was raised to 80 ° C. while stirring at 150 rpm. An initiator aqueous solution in which 40 parts of deionized water and 4 parts of ammonium persulfate were mixed and 1867 parts of a pre-emulsion were dropped in parallel over 3 hours. After completion of dropping the pre-emulsion and the aqueous initiator solution, the temperature was maintained at 80 ° C. for 2 hours. Thereto, 25 parts of a 25% aqueous solution of DMAE (dimethylaminoethanol) was added dropwise over 30 minutes. After completion of the dropwise addition of the DMAE aqueous solution, the temperature was maintained at 80 ° C. for 1 hour, then cooled to room temperature, filtered through 200 mesh, and taken out to obtain an additive emulsion for paint (antifoaming agent). The solid content of the obtained emulsion was 39.8%, the pH was 5.4, and the average particle size of the resin particles was 240 nm. Furthermore, it was 10,500 when the number average molecular weight was calculated | required from the peak of the acrylic resin except the peak of inclusion (antifoaming agent) by GPC analysis.

(Example 2) Preparation of additive for coating material (surface conditioner) emulsified emulsion 267 parts of surface conditioner (manufactured by BYK Japan Japan, trade name BYK-UV3500, non-volatile content 98%) instead of 267 parts of antifoaming agent A pre-emulsion was obtained in the same manner as in Example 1 except that was used. The average particle size of the monomer mixture particles in the pre-emulsion was 300 nm. Further, in the same manner as in Example 1, a coating additive (surface conditioner) -containing emulsion was obtained from this pre-emulsion. The obtained emulsion had a solid content of 39.5%, a pH of 5.5, and an average particle size of the resin particles of 260 nm. Furthermore, it was 10,500 when the number average molecular weight was calculated | required from the peak of the acrylic resin except the peak of inclusion (surface adjustment agent) by GPC analysis.

(Example 3) Preparation of additive-containing emulsion for coating material (leveling agent) 267 parts of leveling agent (trade name BYK-352, non-volatile content 80%, manufactured by BYK Japan KK) instead of 267 parts of antifoaming agent A pre-emulsion was obtained in the same manner as in Example 1 except that. The average particle diameter of the monomer mixture particles in the pre-emulsion was 185 nm. Further, in the same manner as in Example 1, a coating additive (leveling agent) -containing emulsion was obtained from this pre-emulsion. The resulting emulsion had a solid content of 37.9%, a pH of 5.3, and an average particle size of resin particles of 160 nm. Furthermore, it was 10,500 when the number average molecular weight was calculated | required from the peak of the acrylic resin except the peak of inclusion (leveling agent) by GPC analysis.

(Example 4) Preparation of additive for coating material (ultraviolet absorber) embedded emulsion Ultraviolet absorber (Ciba Specialty Chemicals, trade name: Tinuvin 900, non-volatile content: 100%) 267 instead of 267 parts of antifoaming agent A pre-emulsion was obtained in the same manner as in Example 1 except that the part was used. The average particle diameter of the monomer mixture particles in the pre-emulsion was 120 nm. Further, in the same manner as in Example 1, a coating additive (ultraviolet absorber) -containing emulsion was obtained from this pre-emulsion. The obtained emulsion had a solid content of 40.2%, a pH of 5.7, and an average particle size of the resin particles of 130 nm. Furthermore, it was 10,500 when the number average molecular weight was calculated | required from the peak of the acrylic resin except the peak of inclusion (ultraviolet absorber) by GPC analysis.

(Example 5) Preparation of coating additive (antioxidant) -encapsulating emulsion 267 parts of antioxidant (manufactured by Sumitomo Chemical Co., Ltd., trade name Smither WX-R, nonvolatile content 100%) instead of 267 parts of antifoaming agent A pre-emulsion was obtained in the same manner as in Example 1 except that was used. The average particle size of the monomer mixture particles in the pre-emulsion was 145 nm. Further, in the same manner as in Example 1, a coating additive (antioxidant) -containing emulsion was obtained from this pre-emulsion. The resulting emulsion had a solid content of 40.1%, a pH of 5.1, and an average particle size of the resin particles of 150 nm. Furthermore, it was 10,500 when the number average molecular weight was calculated | required from the peak of the acrylic resin except the peak of inclusion (antioxidant) by GPC analysis.

(Comparative Example 1)
A pre-emulsion was obtained in the same manner as in Example 1 except that no antifoam was used. The average particle size of the monomer mixture particles in the pre-emulsion was 160 nm. Further, in the same manner as in Example 1, an emulsion was obtained from this pre-emulsion. The solid content of the obtained emulsion was 34.8%, the pH was 5.6, and the average particle size of the resin particles was 140 nm. Furthermore, it was 10,500 when the number average molecular weight was calculated | required from the peak of the acrylic resin by GPC analysis.

(Example 6)
9.4 parts of a commercially available nonionic anionic dispersant (trade name Disperbyk 190, manufactured by Big Chemie Japan Co., Ltd.), 36.8 parts of ion-exchanged water, 34.5 parts of rutile titanium dioxide, 34.4 parts of barium sulfate, and After preliminarily mixing 6 parts of talc, a glass bead medium was added in a paint conditioner and mixed and dispersed at room temperature until the particle size became 5 μm or less to obtain a colored pigment dispersion paste. Using a laboratory mixer in a stainless steel container, an aqueous coating composition was prepared by mixing 167 parts by mass of the emulsion obtained in Example 1 with 100 parts by mass of the colored pigment dispersion paste and 36 parts by mass of ion-exchanged water. .

  After 200 parts by mass of the obtained aqueous coating composition was filtered with a 200 mesh wire mesh and washed with ion-exchanged water, it was visually evaluated whether or not there was a filtrate on the wire mesh. As a result, no filtrate was observed.

(Example 7)
An aqueous coating composition was prepared in the same manner as in Example 6 except that 167 parts by mass of the emulsion obtained in Example 2 was used instead of 167 parts by mass of the emulsion obtained in Example 1. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, no filtrate was observed.

(Example 8)
An aqueous coating composition was prepared in the same manner as in Example 6 except that 167 parts by mass of the emulsion obtained in Example 3 was used instead of 167 parts by mass of the emulsion obtained in Example 1. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, no filtrate was observed.

Example 9
An aqueous coating composition was prepared in the same manner as in Example 6 except that 167 parts by mass of the emulsion obtained in Example 4 was used instead of 167 parts by mass of the emulsion obtained in Example 1. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, no filtrate was observed.

(Example 10)
An aqueous coating composition was prepared in the same manner as in Example 6 except that 167 parts by mass of the emulsion obtained in Example 5 was used instead of 167 parts by mass of the emulsion obtained in Example 1. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, no filtrate was observed.

(Comparative Example 2)
A colored pigment dispersion paste was obtained in the same manner as in Example 6. Using a lab mixer in a stainless steel container, 125 parts by mass of the emulsion obtained in Comparative Example 1 was added to 100 parts by mass of a colored pigment dispersion paste, a nonionic anionic dispersant (trade name Disperbyk 190, manufactured by Big Chemie Japan Co., Ltd.). By mixing 0.2 parts and 18.7 parts of antifoaming agent (BIC Chemie Japan Co., Ltd., trade name BYK-094, non-volatile content 98%), and further adding 76 parts by mass of ion-exchanged water, and mixing, An aqueous coating composition was prepared. That is, an aqueous coating composition in which a coating additive (antifoaming agent) was not included in resin particles was prepared. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, a filtrate was observed.

(Comparative Example 3)
In the same manner as in Comparative Example 2 except that 18.7 parts of a surface conditioner (manufactured by BYK Japan Japan Co., Ltd., trade name BYK-UV3500, nonvolatile content 98%) was used instead of 18.7 parts of the antifoaming agent, An aqueous coating composition was prepared. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, a filtrate was observed.

(Comparative Example 4)
In the same manner as in Comparative Example 2, except that 18.7 parts of a leveling agent (trade name BYK-352, manufactured by BYK-352, nonvolatile content 80%) 18.7 parts were used instead of 18.7 parts of the antifoaming agent. A coating composition was prepared. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, a filtrate was observed.

(Comparative Example 5)
Comparative Example 2 was used except that 18.7 parts of an ultraviolet absorber (Ciba Specialty Chemicals Co., Ltd., trade name: Tinuvin 900, 100% nonvolatile content) was used instead of 18.7 parts of the antifoaming agent. A water-based coating composition was prepared. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, a filtrate was observed.

(Comparative Example 6)
In the same manner as in Comparative Example 2, except that 18.7 parts of an antioxidant (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumitizer WX-R, 100% nonvolatile content) was used instead of 18.7 parts of the antifoaming agent, An aqueous coating composition was prepared. The obtained aqueous coating composition was subjected to the same evaluation as in Example 6. As a result, a filtrate was observed.

  As is clear from the above-mentioned Examples and Comparative Examples, the aqueous coating composition obtained from the coating additive-containing emulsion of the Examples of the present invention does not form agglomerates and exhibits very good dispersibility. (I.e., the hydrophobic coating additive did not aggregate in water and showed very good dispersibility). Furthermore, the aqueous coating compositions of Examples 6 to 10 of the present invention and the coating films obtained therefrom are respectively defoaming and smooth compared to the aqueous coating compositions of Comparative Examples 2 to 6 and coating films obtained therefrom. It was confirmed that it was excellent in light resistance and light resistance. That is, it was found that by preparing an emulsion in which a coating additive is encapsulated in resin particles, the function of the additive can be sufficiently exhibited as compared with the case where the coating additive is simply dispersed.

The emulsion and aqueous coating composition of the present invention can be suitably used as a coating considering environmental issues.

Claims (8)

An emulsion in which resin particles are dispersed in an aqueous medium,
The resin particles include an outer shell made of resin, and an additive for coating contained in the outer shell,
The solubility of the paint additive in water is less than 1 g / 100 g;
An emulsion in which the average particle size of the resin particles is 100 nm to 500 nm.   The emulsion of Claim 1 whose solid content mass of the said additive for coating materials is 5-80 mass% with respect to the total solid content mass of an emulsion.   The emulsion according to claim 1 or 2, wherein the paint additive is at least one selected from the group consisting of a curing catalyst, an antifoaming agent, a surface conditioner, a leveling agent, an ultraviolet absorber and an antioxidant. .   The emulsion in any one of Claim 1 to 3 whose number average molecular weights of resin which comprises the said outer shell are 3,000-50,000.   The emulsion according to any one of claims 1 to 4, wherein a solubility parameter of a resin constituting the outer shell is 13 or less. An emulsion obtained by a miniemulsion polymerization method in which resin particles are dispersed in an aqueous medium,
The resin particles include an outer shell made of resin, and an additive for coating contained in the outer shell,
The solubility of the paint additive in water is less than 1 g / 100 g;
The average particle diameter of the resin particles is 100 nm to 500 nm,
The outer shell is formed by polymerizing a pre-emulsion in which monomer mixture particles containing the paint additive are dispersed in an aqueous medium. A pre-emulsion in which a coating additive having a solubility in water of less than 1 g / 100 g and a monomer mixture are dispersed in an aqueous medium, and the monomer mixture particles containing the coating additive are dispersed in the aqueous medium. A step of preparing;
Polymerizing the monomer mixture in the pre-emulsion to obtain an emulsion in which resin particles encapsulating the paint additive are dispersed in an aqueous medium,
The method for producing an emulsion, wherein the resin particles have an average particle diameter of 100 nm to 500 nm. An aqueous coating composition containing the emulsion according to any one of claims 1 to 6 and a binder component.